Testing for Healthy Hips, Part One: The Good
Albeit straightforward, we believe the message in our last post is incredibly important: Proper health testing is the most important aspect of breeding quality dogs. Having a sick or disabled family member is heartbreaking, and it’s our responsibility as breeders to minimize those issues. When it comes to Bernedoodles, one of the greatest genetic risks and most dreadful conditions for your dog to develop is hip dysplasia.
Sadly, the testing standard for hip dysplasia utilized by most breeders, OFA, can be described as a “predictive guess” at best, which is a serious issue given the severity of the condition it claims to measure. It’s an even bigger problem when a provenly valid test exists. We want to set the record straight on why PennHip is the only standard you should accept from your breeder as a test for hip dysplasia. Beyond the large body of peer reviewed research that exists on the subject, we have personally seen poor outcomes in the hips of dogs who came from solely OFA tested parents. We don’t want you to suffer the same fate, so we’re publishing a three part series on Canine Hip Dysplasia (CHD) testing. As always, let’s start with the good: PennHip.
Each Tests At-A-Glance
The AIS PennHip procedure is an objective, research-validated test that utilizes imaging and joint distraction to quantify hip laxity and the subsequent risk for CHD. Whew! That’s a mouthful worthy of an undergrad paper. Out of that entire sentence, the only phrase you really need to internalize is “objective, research-validated”. This is the key difference between PennHip and OFA. PennHip is based on original research out of the University of Pennsylvania that subsequent studies have confirmed. It measures an objective joint distraction index that peer-reviewed research has shown correlates heavily to osteoarthritis and CHD. Basically, PennHip is like most tests you experience going to the hospital: Based on measurable data, validated by research and it continues to demonstrate efficacy.
OFA, on the other hand, is the subjective opinion of a single radiographer that looks at a single x-ray and then classifies your dog’s hips on a scale from “Severe” to “Excellent”, with everything from “Fair” to “Good” (is there even a difference?) in between. There is no objective measurement taken from the x-rays, and their classification scale has not a single piece of scientific evidence, let alone peer-reviewed literature, correlating to CHD or arthritis. In short, OFA testing is the hip dysplasia equivalent of letting a doctor assess your cholesterol level by examining your veins without doing any actual blood work. In fact, it’d be like that and then your doctor stating, “Of course this works!” without being able to produce any actual evidence that it does.
Okay, that’s enough OFA bashing, let’s get back to the good and take a look at the actual procedure PennHip utilizes.
The PennHip Testing Protocol
The idea behind a PennHip test is to measure the laxity in your dog’s hip joints. Every dog is born with a different level of connective tissue “looseness” in their hips. Research has shown this laxity is related to the onset and prevalence of CHD throughout a dog’s life. The looser the hip, the more problems a dog will have. As such, the clever folks over at UPenn developed a protocol to consistently and validly measure joint laxity by introducing different forces into the hip while simultaneously taking images.
It starts with the dog being put under mild sedation. While immobile, the certified veterinarian takes three radiographic images of both hips. The first image is of the hip in an extended position, meaning the legs are pulled behind the dog’s hips, similar to when they are running. The second and third radiographs are of the hip in a neutral position, meaning the leg is directly below the hip as if the dog were standing, with two different forces applied. In the second image, the vet introduces a compressive force similar to gravity. In the third, the vet introduces a distraction force, pulling the leg away from the socket at a completely safe intensity. It is worth noting that these forces to the joint are standardized so that all measures maintain consistency and significant conclusions from the data can be made.
These three images are then sent to PennHip’s lab where specialists analyze them. They measure (once again MEASURE, not guess) the distance of between the ball and socket of the joint in extension, compression and distraction. The resulting distraction index (DI), a final number between 0 and 1, objectively demonstrates the looseness of your dog’s hips, with 0 being extremely healthy (tight hips) and 1 being extremely unhealthy (loose hips).
How Does PennHip Make DI Meaningful?
Now, here’s another key point in this conversation: What happens with that data from PennHip vs. OFA? After all, if I told you a dog’s DI is .41, that doesn’t really tell you much if there’s not a bigger picture. An intuitive secret about any test result is that it doesn’t mean anything if you have no other data for comparison. You need data points from other dogs undergoing these tests to understand how DI affects CHD over time. More so, you need as many data points as possible to ensure you’re accurately representing the population of dogs tested.
This is Tillie’s PennHip report. Notice the objective analysis of the DI as well as the qualitative findings on osteoarthritis and cavitation.
Sticking with the doctor metaphor above, if you only tested super athletes’ cholesterol, a superb result would look pretty normal. Conversely, if you only tested obese individuals’ cholesterol, a poor result would look normal. You need data from the entire population for a result to mean anything. This is another way PennHip is far superior to OFA.
For nearly thirty years, PennHip has required every dog’s test results be submitted to their database. This ensures they have a reliable data set to compare a dog’s individual result against. This allows PennHip to quantify exactly how your dog stacks up against the entirety breed data, which allows us breeders to only include dogs that are above the average. This commitment to include every test result is a bold and important feature of PennHip. It doesn’t allow breeders to hide bad testing outcomes, giving a more complete picture to each result. OFA has a slightly lower reporting threshold, and by that I mean they don’t have one, but more on that in our next writeup.
A Quick Look at the Research…
Well, first off, research has validated DI as the most significant factor in predicting osteoarthritis and CHD later in a dog’s life, so what PennHip measures actually correlates to the disease we’re trying to prevent (American Journal of Veterinary Research & Journal of Small Animal Practice). That’s always good news! So then what else does the research show PennHip can tell us? Well, a lot of great things actually. In the interest of brevity, here are a couple key findings.
Pay no attention to the other side of this study showing that OFA does nothing…
The literature supports a few significant correlations between DI and health. First and foremost, lower distraction scores have a significant relationship with hip quality when utilized to select breeding stock (Journal of the American Veterinary Association). That may seem intuitive given the previous findings, but performing more specialized research and seeing a positive result only further reinforces the efficacy of PennHip. Furthermore, DI correlates to specific trends with CHD. Research has shown that PennHip is effective at diagnosing early onset CHD so that you can take preventative action as soon as possible if your dog’s PennHip comes back bad enough (Journal of Small Animal Practice). Conversely, better PennHip scores correlate with a later onset of CHD, or no onset at all, meaning your DI is a good predictor of your dog’s hip function later in life (Veterinary Surgery). Taken all together, PennHip testing predicts the quality of your dogs hips as well as their likelihood and timeline for developing CHD over lifespan.
No, it’s not sexy, but research is important! After all, how else can you know a test works? If you skipped over those last two paragraphs or don’t really care for jargon-centric points, just understand this: PennHip is validated through peer-reviewed research and plenty of it.
The Only Conclusion
The conclusion here is pretty simple. PennHip maintains the scientific standards you’d expect from any kind of health test that is important. It is based on objective measurements gathered with standardized procedures. Research has validated these protocols, and those studies have shown PennHip as an effective CHD assessment for nearly thirty years. In that time, PennHip has compiled a database that includes every result ever gathered, providing a complete data set to compare scores against.
PennHip is the most complete test for hip dysplasia available to breeders, and we are steadfast in our commitment to making it the gold standard by which every program evaluates their dogs. As customers, PennHip should be the only CHD test you give any significance to. I know that might sound extreme given the broad acceptance of OFA in breeding programs, but let us explain. OFA is a grandfathered-in Trojan horse that gives breeders a cheap and easy way to vindicate their dogs’ crappy hips… but let’s leave that to our next post.